Correct. Yet I have read some subsequent discussions about that topic (MWI) and also watched this talk:
What single-world interpretation basically say to fit MWI: All but one world are eliminated by a magic faster than light non-local time-asymmetric acausal collapser-device.
I also read Decoherence is Simple and Decoherence is Falsifiable and Testable.
So far MWI sounds like the most reasonable interpretation to me. And from what I have read I can tell that the sentence - "despite the lack of testable predictions differing from the Copenhagen interpretation" - is not crucial in favoring MWI over other interpretations.
Of course I am not able to judge that MWI is the correct interpretation but, given my current epistemic state, of all interpretations it is the most likely to be correct. For one it sounds reasonable, secondly Yudkowsky's judgement has a considerable weight here. I have no reason to suspect that it would benefit him to favor MWI over other interpretations. Yet there is much evidence that suggests that he is highly intelligent and that he is able to judge what is the correct interpretation given all evidence a non-physicists can take into account.
Edit: "[...] is not correct, or at least not crucial." now reads "[...] is not crucial in favoring MWI over other interpretations."
And from what I have read I can tell that the sentence - "despite the lack of testable predictions differing from the Copenhagen interpretation" - is not correct, or at least not crucial.
It is correct, and it is crucial in the sense that most philosophy of science would insist that differing testable predictions is all that would favor one theory over another.
But other concerns (the Bayesian interpretation of Occam's Razor (or any interpretation, probably)) make MWI preferred.
If you know more Eliezer Yudkowsky facts, post them in the comments.